1. Field of the Invention
The present invention relates to a method of repairing hot section high performance nickel based turbine components using transient liquid phase bonding techniques.
2. Description of the Prior Art
Components of gas turbine engines such as blades and vanes are exposed to a high stress environment which can include mechanical, thermal and rotational stressors. Due to the high cost of high performance hot section turbine components, it is desirable to repair such components rather than replace them. A variety of methods currently exist for repairing gas turbine components.
U.S. Pat. No. 5,913,555 provides a method of repairing worn blade tips of compressor or turbine blades wherein the blade tip is removed, a repair part is machined and attached by welding or soldering.
U.S. Pat. No. 4,326,833 discloses and claims a method for repair of gas turbine engine air cooled blade members which includes removing a blade segment from the blade, providing a replacement member of the same material, size and shape as the removed segment and metallurgically bonding the replacement member through non-fusion techniques.
U.S. Pat. No. 5,033,938 discloses and claims a method of repairing turbine blades comprising removing damaged portions of the turbine blade and forming steel into a shape that conforms to the removed portion, and thereafter welding the insert into the turbine blade.
U.S. Pat. No. 5,822,852 provides a method for repairing blade tips using brazing or welding techniques.
New methods to provide high quality bonding of fabricated repair inserts to pre-existing gas turbine components continue to be sought.
Accordingly, the present invention provides a method of repairing blades and vanes of a gas turbine engine that have been damaged in service or during the manufacturing process, using transient liquid phase bonding techniques. The damaged portion is extracted and an insert of substantially the same material as the component to be repaired is fabricated to replace the damaged part. The insert is joined to the component using transient liquid phase bonding with a bond that is no larger than necessary to bond the insert to the component. The repaired component has a structural bond that closely resembles the base material in structure, mechanical properties and performance. In addition, the bond between the fabricated insert and the component base materials is best formed along bond planes, selected after mechanical and thermal analysis, which are determined to be low stress planes. The bonding of the new part to the old thus takes place in a low stress region having local material requirements significantly below the capabilities of the base material and below the capabilities of the transient liquid phase bond.
It is an object of the invention therefore to provide a method of repairing gas turbines using transient liquid phase bonding techniques.
It is a further object of the invention to repair gas turbines using transient liquid phase bonding techniques with bond planes located in regions of low mechanical and thermal stress.
It is an additional object of the invention to provide a repaired gas turbine engine component having a repair bond that closely matches the structural, mechanical and performance properties of the base material.
These and other objects of the invention will become evident from the description, the drawings and the appended claims.